if the market's response for the changes in market values in response to the rumors of a pending offer and the initial offer is not the consistent

if the market's response for the changes in market values in response to the rumors of a pending offer and the initial offer is not the consistent with the valuation of the projected merger benefits, what are the possible reasons ?

The real market reaction has been a rise in share prices, eg. from $86.97 to $92.49